[Xen-changelog] [xen stable-4.10] x86/HVM: account for fully eager FPU mode in emulation

[patchbot@xxxxxxx]

commit eeb15764adbfe44e9f11a68e2444f4ba12b3cf1d
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jun 15 13:43:43 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jun 15 13:43:43 2018 +0200

    x86/HVM: account for fully eager FPU mode in emulation
    
    In fully eager mode we must not clear fpu_dirtied, set CR0.TS, or invoke
    the fpu_leave() hook. Instead do what the mode's name says: Restore
    state right away.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: e23d2234e08872ac1c719f3e338994581483440f
    master date: 2018-06-15 11:49:06 +0200
---
 xen/arch/x86/hvm/emulate.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 131480fdd9..9a2ed5209d 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1991,13 +1991,20 @@ static void hvmemul_put_fpu(
     if ( backout == X86EMUL_FPU_fpu )
     {
         /*
-         * To back out changes to the register file simply adjust state such
-         * that upon next FPU insn use by the guest we'll reload the state
-         * saved (or freshly loaded) by hvmemul_get_fpu().
+         * To back out changes to the register file
+         * - in fully eager mode, restore original state immediately,
+         * - in lazy mode, simply adjust state such that upon next FPU insn
+         *   use by the guest we'll reload the state saved (or freshly loaded)
+         *   by hvmemul_get_fpu().
          */
-        curr->fpu_dirtied = false;
-        stts();
-        hvm_funcs.fpu_leave(curr);
+        if ( curr->arch.fully_eager_fpu )
+            vcpu_restore_fpu_eager(curr);
+        else
+        {
+            curr->fpu_dirtied = false;
+            stts();
+            hvm_funcs.fpu_leave(curr);
+        }
     }
 }
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.10

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